Metal stack for local interconnect layer

Abstract

In one embodiment, a local interconnect layer in an integrated circuit is formed by depositing a first film over an oxide layer and depositing a second film over the first film. The first film may comprise titanium nitride, while the second film may comprise tungsten, for example. The first film and the second film may be deposited in-situ by sputtering. The second film may be etched using the first film as an etch stop, and the first film may be etched using the oxide layer as an etch stop.

What is claimed is:  
     
       1. A method of forming a local interconnect layer in an integrated circuit, the method comprising: 
       depositing a first film over an oxide layer, the first film comprising titanium nitride; and  
       depositing a second film over the first film, the second film comprising tungsten, the first film and the second film forming a metal stack of the local interconnect layer.  
     
     
       2. The method of  claim 1  wherein the first film and the second film are deposited in-situ. 
     
     
       3. The method of  claim 1  wherein the first film and the second film are deposited using a sputtering process. 
     
     
       4. The method of  claim 1  wherein the first film and the second film from a metal stack having a thickness equal to or less than about 600 Angstroms. 
     
     
       5. The method of  claim 1  wherein the first film is deposited to a thickness equal to or less than about 300 Angstroms. 
     
     
       6. The method of  claim 1  wherein the second film is deposited to a thickness equal to or less than about 300 Angstroms. 
     
     
       7. The method of  claim 1  wherein each of the first film and the second film is deposited to a thickness of about 300 Angstroms. 
     
     
       8. The method of  claim 1  wherein the first film and the second film form a metal stack having a sheet resistance equal to or less than about 10 Ohm/sq. 
     
     
       9. The method of  claim 1  further comprising: 
       etching the second film to stop on the first film; and  
       etching the first film to stop on the oxide layer.  
     
     
       10. The method of  claim 9  wherein the oxide layer is over a semiconductor substrate. 
     
     
       11. The method of  claim 1  further comprising: 
       etching the second film with a fluorine-based etchant.  
     
     
       12. The method of  claim 1  further comprising: 
       etching the first film with a chlorine-based etchant.  
     
     
       13. The method of  claim 1  further comprising: 
       probing the second film to electrically test the metal stack.  
     
     
       14. The method of  claim 1  further comprising: 
       depositing a resist material over the second film.  
     
     
       15. A method of forming a local interconnect layer in an integrated circuit, the method comprising: 
       sputtering a first film over an oxide, the first film comprising titanium nitride;  
       sputtering a second film over the first film in a same tool employed to sputter the first film, the second film comprising tungsten, the first film and the second film forming a metal stack of the local interconnect layer.  
     
     
       16. The method of  claim 15  wherein the first film and the second film form a metal stack having a thickness equal to or less than about 600 Angstroms. 
     
     
       17. The method of  claim 15  further comprising: 
       probing the second film to electrically test the material stack.